From: Matthew Wilcox <willy@infradead.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>,
Ming Mao <maoming.maoming@huawei.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
linux-mm@kvack.org, alex.williamson@redhat.com,
akpm@linux-foundation.org, cohuck@redhat.com,
jianjay.zhou@huawei.com, weidong.huang@huawei.com,
peterx@redhat.com, aarcange@redhat.com, wangyunjian@huawei.com,
jhubbard@nvidia.com
Subject: Re: [PATCH V4 1/2] vfio dma_map/unmap: optimized for hugetlbfs pages
Date: Wed, 9 Sep 2020 16:00:15 +0100 [thread overview]
Message-ID: <20200909150015.GI6583@casper.infradead.org> (raw)
In-Reply-To: <20200909142941.GA23553@infradead.org>
On Wed, Sep 09, 2020 at 03:29:41PM +0100, Christoph Hellwig wrote:
> On Wed, Sep 09, 2020 at 10:05:18AM -0300, Jason Gunthorpe wrote:
> > How to use? The VMAs can have mixed page sizes so the caller would
> > have to somehow switch and call twice? Not sure this is faster.
>
> We can find out the page size based on the page. Right now it is
> rather cumbersome, but one of willys pending series has a nicer helper
> for that.
Actually already merged. There's page_size() which went into 5.4, and
is the one you'd want to use (also page_shift() and compound_nr()).
The thp_* equivalents (merged in 5.9) compile away to nothing if you
don't have CONFIG_TRANSPARENT_HUGEPAGE enabled, but since there are
many ways of getting a compound page mapped into userspace, page_size()
is the helper to use for VFIO.
next prev parent reply other threads:[~2020-09-09 15:00 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-08 13:32 [PATCH V4 0/2] vfio: optimized for hugetlbf pages when dma map/unmap Ming Mao
2020-09-08 13:32 ` [PATCH V4 1/2] vfio dma_map/unmap: optimized for hugetlbfs pages Ming Mao
2020-09-09 8:01 ` Christoph Hellwig
2020-09-09 13:05 ` Jason Gunthorpe
2020-09-09 14:29 ` Christoph Hellwig
2020-09-09 15:00 ` Matthew Wilcox [this message]
2020-09-09 15:09 ` Jason Gunthorpe
2020-09-09 13:41 ` Matthew Wilcox
2020-09-09 17:04 ` Matthew Wilcox
2020-09-08 13:32 ` [PATCH V4 2/2] vfio: optimized for unpinning pages Ming Mao
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